To repair there are two methods available on market first is use manual method and second is use any third party tool. you can use manual method but sometime manual method is failed to
repair all pst files then in this situation i personally recommend you this brilliant third party Outlook pst recovery software to repair severely corrupted PST files, restore deleted items, and export PST to Office 365, Live Exchange Server, and new PST. Using this tool, Outlook users can also save PST to EML, MSG, HTML, RTF, Cal, vCal, and vCard format. With it reliable interface all users both technical or non technical can easily use this tool without any technical skill. it provide free demo version which allow the users to see the preview of all recoverable data.